function以下是tokenerc20的0.4.16的標準pragma solidity ^0.4.16;inte***ce
tokenrecipient
contract tokenerc20
/*** internal transfer, only can be called by this contract
*/function
_transfer
(address _from, address _to, uint _value)
internal
/*** transfer tokens
** send `_value` tokens to `_to` from your account
** @param _to the address of the recipient
* @param _value the amount to send
*/function
transfer
(address _to, uint256 _value)
public
/*** transfer tokens from other address
** send `_value` tokens to `_to` on behalf of `_from`
** @param _from the address of the sender
* @param _to the address of the recipient
* @param _value the amount to send
*/function
transferfrom
(address _from, address _to, uint256 _value)
public
returns
(bool success)
/*** set allowance for other address
** allows `_spender` to spend no more than `_value` tokens on your behalf
** @param _spender the address authorized to spend
* @param _value the max amount they can spend
*/function
(address _spender, uint256 _value)
public
returns
(bool success)
/*** set allowance for other address and notify
** allows `_spender` to spend no more than `_value` tokens on your behalf, and then ping the contract about it
** @param _spender the address authorized to spend
* @param _value the max amount they can spend
*/function
(address _spender, uint256 _value, bytes _extradata)
public
returns
(bool success)
}/**
* destroy tokens
** remove `_value` tokens from the system irreversibly
** @param _value the amount of money to burn
*/function
burn
(uint256 _value)
public
returns
(bool success)
/*** destroy tokens from other account
** remove `_value` tokens from the system irreversibly on behalf of `_from`.
** @param _from the address of the sender
* @param _value the amount of money to burn
*/function
burnfrom
(address _from, uint256 _value)
public
returns
(bool success)
}
在審計過程中 發現1、轉帳時判斷require
(_to !=
0x0);的寫法換成 require
(_to !=
address(0)
);也可以
避免轉帳將幣轉丟如上圖的 _transfer 或下圖：
transfer(address _to, uint256 _value)
public
returns (bool)
2、在0.4.20以上，為了避免重名的事件和函式引起混用，增加dao風險等事件使用 event 函式使用emit如：event burn(address indexed from, uint256 value);emit burn(_from, _value);3、建議對
newowner 進行判斷 避免空位址 將所有權更換丟//如require(newowner!= address(0));
contract owned modifier onlyowner
function
transferownership
(address newowner)
onlyowner
public
}中 4、事務順序依賴
5、時間依賴順序
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